High blood pressure (including essential hypertension) is a major risk factor for stroke, congestive heart failure and coronary heart disease. Heredity plays a large and important role in blood pressure level particularly as it relates to hypertension. In the proposed study, the mode of inheritance of genes controlling blood pressure and related variables will be investigated (i.e., their genetic component determined). This will be accomplished by using recently developed statistical methods designed for segregation and linkage analysis of quantitative traits. In the proposed study we will analyze blood pressure and related variables of an anthropometric, biochemical and physiological nature, e.g., subcutaneous fat thickness, Dopamine-beta hydroxylase activity, Kallikrein levels, blood lipid and lipoprotein levels, responses to certain stress, etc. They will be measured in several very large, multigeneration families ascertained via hypertensive probands, equally representing black and white racial groups. Blood samples from these families will be analyzed for as many polymophic genetic markers as possible and linkage relationships between hypertension or hypertension-related variables and each of the genetic markers will be investigated. In meeting our objectives we will help to define factors related to increased risk of hypertension; that help account for differences in blood pressure among various subgroups of the population; and, perhaps most importantly, that can be used to identify children that have a high risk of developing hypertension as adults.